A patent document 1 discloses a commonly used transfer (driving force distribution device) of a four wheel drive vehicle. The driving force distribution device disclosed in this document is a transfer of a four wheel drive vehicle, which employs a planetary gearset, and sets driving force distribution between main and auxiliary driving wheels wherein a torque from a transmission is inputted into a carrier of the planetary gearset, and the torque is split and outputted from the carrier through a sun gear and a ring gear to the main driving wheels and the auxiliary driving wheels.
Patent Document 1: JP 2005-337442 A